////
/// @group helpers
////

/// Media query for retina images (device-pixel-ratio)
///
/// @param {Number} $ratio [2] - Device pixel ratio
/// @content Passed content will be outputted within the media query
///
/// @example scss - Providing a @2x image for screens that support it
///   background-image: govuk-image-url("my-image.png");
///
///   @include govuk-device-pixel-ratio {
///     background-image: govuk-image-url("my-image-2x.png");
///   }
///
/// @example scss - Using a custom ratio
///   background-image: govuk-image-url("my-image.png");
///
///   @include govuk-device-pixel-ratio {
///     background-image: govuk-image-url("my-image-2x.png");
///   }
///
///   @include govuk-device-pixel-ratio(3) {
///     background-image: govuk-image-url("my-image-3x.png");
///   }
///
/// @access public

@mixin govuk-device-pixel-ratio($ratio: 2) {
  @media only screen and (-webkit-min-device-pixel-ratio: $ratio),
    only screen and (-o-min-device-pixel-ratio: #{($ratio * 10)} / 10),
    only screen and (min-resolution: #{($ratio * 96)}dpi),
    only screen and (min-resolution: #{$ratio}dppx) {
    @content;
  }
}
